If writer-director David Lebrun’s Proteus seems by turns like conventional biographical documentary, cleverly curated museum show, animated lecture in an upper-level college survey course, and precision instrument of trance induction, that’s just as it should be. The film borrows its name from the Greek sea god famous for assuming an infinite number of forms. Ernst Haeckel, a founding father of ecology, liked that name too, and accordingly coined the term “protists” (later “protozoa”) after discovering and describing thousands of these unicellular creatures. Lebrun’s movie tells–and, importantly, shows–Haeckel’s story. It involves Goethe’s Faust, Coleridge’s Ancient Mariner, and the occasional trippy montage of lovely, grotesque, endlessly shapeshifting microscopic organisms, all set to Yuval Ron’s expansive yet restrained score. The result is a bewitching, cinematically fluent unification of scientific method and creative imagination.